Protungulatum (latest Cretaceous) -- Transitional between earliest placental mammals and the condylarths (primitive, small hoofed animals). These early, simple insectivore- like small mammals had one new development: their cheek teeth had grinding surfaces instead of simple, pointed cusps. They were the first mammal herbivores. All their other features are generalized and primitive -- simple plantigrade five-toed clawed feet, all teeth present (3:1:4:3) with no gaps, all limb bones present and unfused, pointy-faced, narrow small brain, eyesocket not closed.

Curiously Protungulatum is only followed by a description of what is supposed to come after it but no actual connections are made.

The most common fossil mammal from the lower Eocene is a little primitive weasel-looking condylarth called Hyopsodus. It was previously known that many very different species of Hyopsodus were found at different sites, with (for example) very different tooth size. In 1976, Gingerich analyzed the tooth size of all the known fossils of Hyopsodus that could be dated reliably and independently. He found that "the pattern of change in tooth size that emerges is one of continuous gradual change between lineages, with gradual divergence following the separation of new sister lineages." When tooth size is charted against time, it shows the single lineage smoothly splitting into four descendant lineages. (This was one of the first detailed & extensive studies of speciation.)

By 1985, Gingerich had many more specimens of Hyopsodus and of several other Eocene condylarth lineages as well, such as Haplomylus. For example: "[ Haplomylus speirianus] ...gradually became larger over time, ultimately giving rise to a new species Haplomylus scottianus... Hyopsodus latidens also became larger and then smaller, ultimately giving rise to a still smaller species, Hyopsodus simplex." These analyses were based on hundreds of new specimens (505 for Haplomylus, and 869 for Hyposodus) from Clark's Fork Basin in Wyoming. Note, however, that several other species from the same time showed stasis (particularly Ectocion, which was previously reported to show change, but in fact stayed much the same), and that not all species transitions are documented. So transitions are not always found. But sometimes they are found.

Haplomylus and Hyposodus are two different genera with no evidence given of a connection between them. The only evidence of actual connections are within each genus. This is not a problem for creation since they are probably all the same kind.